Yellowing

Yellowing

Definition

Yellowing refers to the undesirable discoloration of art materials, typically appearing as a yellow or brown tint. This effect is primarily caused by the presence of acidic substances or lignin in paper, board, or other substrates, and is accelerated by environmental factors such as UV light, oxygen, and fluctuating humidity.

Causes

• Acidic content in paper, mat board, or adhesives.
• Lignin breakdown in wood-based or non-archival materials.
• Exposure to ultraviolet (UV) light.
• Oxidation and air pollutants.
• High or fluctuating relative humidity levels.

Effects

• Visual degradation of paper, photographs, and other substrates.
• Reduction in aesthetic quality of artwork or framed materials.
• Potential weakening of fibers over time.

Prevention and Mitigation

• Use acid-free and lignin-free mats, boards, and adhesives.
• Incorporate UV-filtering glazing such as conservation acrylic or museum glass.
• Maintain controlled climate conditions with stable temperature and relative humidity.
• Store artworks away from direct sunlight and pollutants.

Related Terms

• Leeching
• Acid Outgassing
• Lignin
• Deterioration